The present invention related to dental equipment, and more particularly, to teaching tools for the use of endodontic apical location equipment.
During certain dental procedures, the pulp of the tooth must be removed and other procedures must be performed on the root canal. Persons training to become dentists must learn how to properly remove such pulp and perform the other necessary procedures. Precise location of the root apex is vitally important for the correct endodontic treatment of a tooth. Pulp tissue is richly vascularized and innervated and is contained in the pulp cavity inside the tooth including in the pulp chamber and in pulp canals in tooth roots. The pulp canals are often referred to as root canals. If the endodontic procedure of extracting and cleaning the pulp tissue from a root pulp canal is performed at a length short of the apex, pulp tissue may remain in the canal. Failure to remove all pulp tissue may lead to infection and pain for the patient and necessitate additional surgery. If the endodontic procedure is performed beyond the length of the root apex, the reamer may penetrate into the periodontal ligament leading to pain and extreme sensitivity to the patient. Therefore, current endodontic procedures normally require the careful locating of the root apex at the base of the pulp canal before the reamer or other tools are used to enlarge the pulp canal.
Multiple methods are currently utilized to determine the location of the apex during an endodontic procedure on a live patient. One procedure is the use of x-ray radiographs of the tooth while a metal endodontic reamer is located in the root canal. This allows the dentist to visually compare the length of the metal reamer to the location of the end of the root to determine the location of the root apex. This method is often unreliable and not cost-effective.
A second method is to use an electrically aided apical position location. Certain electronic aids and methods of their use include those described in U.S. Pat. No. 5,759,159 to Masreliez, U.S. Pat. No. 5,211,556 to Kobayashi et al, and U.S. Pat No. 6,059,569 to Otsuka, all incorporated herein by reference. These patents describe apical position locators utilizing impedance measurements to determine the location of the apex that use electrical conductance. In the electrical conductance approach, an electrically-conductive probe is inserted into the root pulp canal and a second electrode is attached to the patient's body, such as by hanging a hook-shaped electrode from the patient's mouth. As the probe is inserted into the root pulp canal and advanced through the root pulp canal to the root apex, the electrical impedance between the probe and the electrode is continuously measured. The electrical impedance is greater when there is little conductance between the probe and the electrode, such as when the probe is in the pulp canal, and lower when there is greater conductance between the probe and the electrode, such as when the probe touches the tissue at the bottom of the pulp canal that is much more conductive than the pulp canal itself. Once the impedance lowers and reaches a predetermined range or value, the location of the apex is indicated and the depth of the probe is noted for future use with other instruments. The electrical approach using impedance for determining apex location is currently the preferred and standard technique used in endodontic practice and taught in dental schools.
Instruction in the use of electrical apical position locators has generally required practice upon live patients in need of endodontic treatment. Performing endodontic procedures on healthy teeth is unethical and represents dental malpractice. Endodontic patients are often in pain prior to seeing the dentist, and are usually apprehensive about the endodontic procedure and less than enthusiastic about serving as subjects in dental instruction on the use of apical position locators. The additional pain which may be encountered, or the mere potential for such additional pain, results in few such patients volunteering to allow students to perform the procedure.
The number of endodontic procedures that a dental student or a doctoral student in general dentistry performs on live patients is severely limited by the number of willing participants in need of such procedures. Dental students and general dentists would benefit from additional training and instruction in the use of apical position locators in a realistic setting. In turn, the endodontic patient would benefit from the additional training received by the practitioner.
Prior to this invention, no adequate surrogate for the live patient has been developed for instruction in the use of electrical apical position locators. U.S. Pat. No. 5,503,562 described a transparent endodontic inspection block which allows the dental student to simulate the cleaning out the root pulp canal. The student utilizing the inspection block could look through the side of the inspection block and locate the root apex. This invention is not designed to train apex location techniques and does not represent realistic conditions of endodontic treatment. U.S. Pat. No. 4,137,633, issued in 1979, disclosed a resilient mass located at the apex of a block of transparent material to simulate the tactile sensation of the periodontal membrane located at the apex of a natural tooth. Thus, prior devices permitted students to visually locate a simulated apex through the addition of a resilient mass located at the apex. However, no known prior devices have disclosed providing a simulation of a live tooth and human tissue to practice using an electrical apical position locator.
Additionally, during training to do such procedures, it is important to have the procedure simulated on an actual patient, as much as possible, so that the student can learn how to overcome problems of working in the patient's mouth. Therefore, it is also desirable to provide a training device that can be utilized for at least some of the student endodontic procedures and which simulates a live patient, as much as possible.
In addition to the need for a training device for use in teaching root canal procedures, it is also desirable to have such a device that can be used to teach other types of procedures such as how to treat dental decay and how to do crown and bridge procedures. Because training devices may be expensive for the student, it is preferable that the device allow the student to practice different types of procedures which preferably require somewhat different structure. Root canal procedures require real or artificial teeth having a root and with structure allowing electrical conductance. Crown and bridge work require a section of teeth wherein one or more is missing and real or artificial teeth can be modified to accept a bridge with a skin like structure over the gum, as it is important for the student to correctly interface the bridge with the skin. Dental decay procedures do not require a root or electrical conductance, but preferably utilizes real or artificial teeth that are mounted in such a manner so as to simulate the interaction of the teeth with each other and with ligament tissue that normally holds such teeth in place. Each of these and other procedures are preferably performed on separate or different practice units to allow the student the best range of training.
Furthermore, it is desirable that the different sections be modular so that a student can preform one, two or all procedures within a single assembly. For example, when working on one procedure, all the individual modular inserts in an assembly may be designed for a single procedure to provide multiple locations to practice or such can be changed to provide modular inserts for multiple procedures for practice or testing. Because the individual modular inserts can be easily changed, when one is used and is not reusable, it can easily be replaced by another without requiring that the entire assembly be discarded.